Human health is imped by many microbial entities. Inoculation by viruses and bacteria cause a wide variety of sicknesses and ailments. Media attention to cases of food poisoning, strep infections, and the like is increasing public awareness of microbial issues.
It is well known that the washing of hard surfaces, food (e.g. fruit or vegetables) and skin, especially the hands, with antimicrobial or non-medicated soap, can remove many viruses and bacteria from the washed surfaces. Removal of the viruses and bacteria is due to the surfactancy of the soap and the mechanical action of the wash procedure. Therefore, it is known and recommended that people wash frequently to reduce the spread of viruses and bacteria.
Bacteria found on the skin can be divided into two groups: resident and transient bacteria. Resident bacteria are Gram positive bacteria which are established as pennanent microcolonies on the surface and outermost layers of the skin and play an important, helpful role in preventing the colonization of other, more harmful bacteria and fungi.
Transient bacteria are bacteria which are not part of the normal resident flora of the skin, but can be deposited when airborne contaminated material lands on the skin or when contaminated material is brought into physical contact with it. Transient bacteria are typically divided into two subclasses: Gram positive and Gram negative. Gram positive bacteria include pathogens such as Staphylococcus aureus, Streptococcus pyogenes and Clostridium botulinum. Gram negative bacteria include pathogens such as Salmonella, Escherichia coli, Klebsiella, Haemophilus, Pseudomonas aeruginosa, Proteus and Shigella dysenteriae. Gram negative bacteria are generally distinguished from Gram positive by an additional protective cell membrane which generally results in the Gram negative bacteria being less susceptible to topical antibacterial actives.
Antimicrobial cleansing products have been marketed in a variety of forms, for some time. Forms include antibacterial soaps, hard surface cleaners, and surgical disinfectants. Rinse-off antimicrobial soaps have been formulated to provide bacteria removal during washing. They have been shown to also provide a residual effectiveness against Gram positive bacteria. Antimicrobial active agents are deposited on the washed surface during the washing process. The residual active controls the colonization and growth of some surviving and some newly contacted transient bacteria. For example, antibacterial soap, when used regularly in hand washing, has been found to provide a 1.0 log to 1.5 log reduction (i.e 90 to 97% reduction) residual effectiveness against Gram positive bacteria after two to five hours. That is skin washed with antibacterial soap, was tested two to five hours later, to be contaminated with only from 3 to 10% of the number of Gram positive bacteria compared to skin washed with a placebo soap, depending on the test protocol and bacteria tested. Antimicrobial liquid cleansers are disclosed in U.S. Pat. No. 4,847,072, Bissett et al., issued Jul. 11, 1989, U.S. Pat. No. 4,939,284, Degenhardt, issued Jul. 3, 1990 and U.S. Pat. No. 4,820,698, Degenhardt, issued Apr. 11, 1989, all patents being incorporate herein by reference. Finally, these traditional antimicrobial soaps have been developed for use in a washing process with water. This limits their use to locations with available water.
Some of these traditional products, especially the hard surface cleaners, surgical disinfectants, and some alcohol-based leave-on lotions (e.g. Purell.RTM.), utilize high levels of alcohol and/or harsh surfactants which have been shown to dry out and irritate skin tissues. Ideal personal cleansers should gently cleanse the skin, cause little or no irritation, and not leave the skin overly dry after frequent use and preferably should provide a moisturizing benefit to the skin.
Leave-on, topical lotions, foams and gels have been used, in the past, to moisturize skin, along with a variety of other purposes. However, these leave-on compositions provide minimal residual effectiveness versus transient Gram positive bacteria.
PCT application WO 92/18100, Keegan et al., published Oct. 29, 1992 and PCT application WO 95/32705, Fujiwara et al., published Dec. 7, 1995 teach liquid skin cleansers comprising mild surfactants, antibacterial agents and acidic compounds to buffer the pH, which provide improved germ hostility. However, the use of the acid compounds for only pH adjustment therein, result in compositions which do not deliver the undissociated acid required to provide residual effectiveness versus Gram positive bacteria. This situation is compounded in Keegan and Fujiwara by the preference of mild surfactants, including nonionic surfactants. Neither Keegan nor Fujiwara teach the use of their compositions in a form which can be used without available water, e.g. a leave-on lotion.
U.S. Pat. No. 3,141,821, issued to Compeau Jul. 21, 1964 and Irgasan DP 300 (Triclosan.RTM.) technical literature from Ciba-Giegy, Inc., "Basic Formulation for Hand Disinfection 89/42/01" teach the use of anionic surfactants, antimicrobial actives and acids in antibacterial skin cleansers. However, the selection of highly active surfactants result in leave-on compositions which are drying and harsh to the skin. Here, also, neither reference teaches the use of antimicrobial compositions in a form which can be used without available water, e.g. a a leave-on lotion.
Given the health impacts of bacteria like Staphylococcus aureus, Streptococcus pyogenes and Clostridium botulinum, it would be highly desirable to formulate leave-on, topical antimicrobial compositions which provide improved residual effectiveness versus these resident and transient Gram positive bacteria, which are also mild to the skin and which can be used without water. Existing products have been unable to deliver all of these benefits.
Applicants have found that leave-on, topical antimicrobial compositions which provide such mildness and a new level of residual effectiveness versus Gram positive bacteria, can be formulated by using known antimicrobial actives in combination with specific organic and/or inorganic acids as proton donating agents, and specific anionic surfactants, all of which are deposited on the skin. The deposited proton donating agent and anionic surfactant work in combination with the selected active, to provide a new level of hostility to bacteria contacting the skin.